Reference counting in general has been an interest of mine since even when I'm writing server-side software it's usually pathological-case latency rather than raw throughput that really matters.

It's a pity that it's mostly C++ (smart pointers) and Obj-C (ARC) that have access to this.

( I say this realizing Python is hybridized. )

Edit: Most of my hesitations regarding using the JVM have to do with how incredibly finicky tuning it can be.